Infrared spectroscopic study on chemical and phase equilibrium in triethylammonium acetate

Changes in microstructure of two ammonium‐based protic ionic liquids proved by in situ variable‐temperature 1H NMR spectroscopy: influence of anion

“…For pure PILs, MacFarlane and Seddon consider them as complex liquids in which a variety of proton transfer and association equilibrium are likely to be established . The studies concerning the equilibrium in PILs caught much attention by many researchers . To our knowledge, the strength of hydrogen bond interaction not only has an important influence on the microstructure of PILs but also relates to the proton transfer from cation to anion or dissociation–association equilibrium.…”

“…Apart from the microstructure of PILs with solvents, there has been a growing interest in the study of the microstructure of pure PILs. Accordingly, the interactions between cation and anion in pure PILs consist of a mixture of hydrogen bonds, Coulomb charge, and dispersion forces have been investigated using a variety of spectroscopic techniques and theoretical calculations . The results indicated that hydrogen bond interactions between the available proton of cation and anion played an important role in the microstructure of pure PILs, which might lead to form of the contact ion‐pair, dissociated ion‐pair, and neutral species in liquid state, and even to form of neutral molecular aggregates in the gas phase, making it difficult to quantify and define the ionicity of PILs .…”

Structural Features of Triethylammonium Acetate through Molecular Dynamics

“…The separated contributions due to the two species are reported in the bottom panel, where one can see that the TEA/TEAH + contributes only in a minor way to the IR spectrum (red line). Following the assignment of [25], one can see that the only visible band from TEAH + is the one located between 1350 and 1400 cm −1 , which is attributed to NH 3 + deformations. The AcOH/AcOmoiety represents the major source of IR absorption in the fluid and contributes to all the major bands in the 1000-2000 cm −1 region: one can clearly recognize the C=O absorption due to carboxyl stretching between 1600 and 1700; the C-O stretching of the carboxyl between 1200 and 1300; and the two stretching modes of the carboxylate at 1350 and 1500, which are red-shifted by the presence of H-bonds.…”

“…The AcOH/AcOmoiety represents the major source of IR absorption in the fluid and contributes to all the major bands in the 1000-2000 cm −1 region: one can clearly recognize the C=O absorption due to carboxyl stretching between 1600 and 1700; the C-O stretching of the carboxyl between 1200 and 1300; and the two stretching modes of the carboxylate at 1350 and 1500, which are red-shifted by the presence of H-bonds. The calculated spectrum can be compared with the experimental one reported in [25] in Figure 3. Apart from the intensity of certain bands, the agreement in the position and number of visible bands is very good over the whole fingerprint region.…”

“…It is thus instructive to study such a relatively simple system in order to understand the behavior of those substances that lie at the border of the ionic and polar regimes. Two papers [25,26] have appeared recently in which a set of experimental determinations of this liquid have been performed. The former presented an analysis by means of IR spectral measurements; the latter investigated in more detail the structure of the liquid.…”